/*
Copyright 2014 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package cmd

import (
	"fmt"
	"io"
	"reflect"
	"strings"

	jsonpatch "github.com/evanphx/json-patch"
	"github.com/golang/glog"
	"github.com/spf13/cobra"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/json"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/strategicpatch"
	"k8s.io/apimachinery/pkg/util/yaml"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/kubectl"
	"k8s.io/kubernetes/pkg/kubectl/cmd/templates"
	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
	"k8s.io/kubernetes/pkg/kubectl/resource"
	"k8s.io/kubernetes/pkg/kubectl/util/i18n"
	"k8s.io/kubernetes/pkg/printers"
)

var patchTypes = map[string]types.PatchType{"json": types.JSONPatchType, "merge": types.MergePatchType, "strategic": types.StrategicMergePatchType}

// PatchOptions is the start of the data required to perform the operation.  As new fields are added, add them here instead of
// referencing the cmd.Flags()
type PatchOptions struct {
	resource.FilenameOptions

	Local bool

	OutputFormat string
}

var (
	patchLong = templates.LongDesc(i18n.T(`
		Update field(s) of a resource using strategic merge patch

		JSON and YAML formats are accepted.

		Please refer to the models in https://htmlpreview.github.io/?https://github.com/kubernetes/kubernetes/blob/HEAD/docs/api-reference/v1/definitions.html to find if a field is mutable.`))

	patchExample = templates.Examples(i18n.T(`
		# Partially update a node using strategic merge patch
		kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}'

		# Partially update a node identified by the type and name specified in "node.json" using strategic merge patch
		kubectl patch -f node.json -p '{"spec":{"unschedulable":true}}'

		# Update a container's image; spec.containers[*].name is required because it's a merge key
		kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'

		# Update a container's image using a json patch with positional arrays
		kubectl patch pod valid-pod --type='json' -p='[{"op": "replace", "path": "/spec/containers/0/image", "value":"new image"}]'`))
)

func NewCmdPatch(f cmdutil.Factory, out io.Writer) *cobra.Command {
	options := &PatchOptions{}

	// retrieve a list of handled resources from printer as valid args
	validArgs, argAliases := []string{}, []string{}
	p, err := f.Printer(nil, printers.PrintOptions{
		ColumnLabels: []string{},
	})
	cmdutil.CheckErr(err)
	if p != nil {
		validArgs = p.HandledResources()
		argAliases = kubectl.ResourceAliases(validArgs)
	}

	cmd := &cobra.Command{
		Use:     "patch (-f FILENAME | TYPE NAME) -p PATCH",
		Short:   i18n.T("Update field(s) of a resource using strategic merge patch"),
		Long:    patchLong,
		Example: patchExample,
		Run: func(cmd *cobra.Command, args []string) {
			options.OutputFormat = cmdutil.GetFlagString(cmd, "output")
			err := RunPatch(f, out, cmd, args, options)
			cmdutil.CheckErr(err)
		},
		ValidArgs:  validArgs,
		ArgAliases: argAliases,
	}
	cmd.Flags().StringP("patch", "p", "", "The patch to be applied to the resource JSON file.")
	cmd.MarkFlagRequired("patch")
	cmd.Flags().String("type", "strategic", fmt.Sprintf("The type of patch being provided; one of %v", sets.StringKeySet(patchTypes).List()))
	cmdutil.AddPrinterFlags(cmd)
	cmdutil.AddRecordFlag(cmd)
	cmdutil.AddInclude3rdPartyFlags(cmd)

	usage := "identifying the resource to update"
	cmdutil.AddFilenameOptionFlags(cmd, &options.FilenameOptions, usage)

	cmd.Flags().BoolVar(&options.Local, "local", false, "If true, patch will operate on the content of the file, not the server-side resource.")

	return cmd
}

func RunPatch(f cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []string, options *PatchOptions) error {
	switch {
	case options.Local && len(args) != 0:
		return fmt.Errorf("cannot specify --local and server resources")
	}

	cmdNamespace, enforceNamespace, err := f.DefaultNamespace()
	if err != nil {
		return err
	}

	patchType := types.StrategicMergePatchType
	patchTypeString := strings.ToLower(cmdutil.GetFlagString(cmd, "type"))
	if len(patchTypeString) != 0 {
		ok := false
		patchType, ok = patchTypes[patchTypeString]
		if !ok {
			return cmdutil.UsageErrorf(cmd, "--type must be one of %v, not %q",
				sets.StringKeySet(patchTypes).List(), patchTypeString)
		}
	}

	patch := cmdutil.GetFlagString(cmd, "patch")
	if len(patch) == 0 {
		return cmdutil.UsageErrorf(cmd, "Must specify -p to patch")
	}
	patchBytes, err := yaml.ToJSON([]byte(patch))
	if err != nil {
		return fmt.Errorf("unable to parse %q: %v", patch, err)
	}

	// TODO: fix --local to work with customresources without making use of the discovery client.
	// https://github.com/kubernetes/kubernetes/issues/46722
	builder, err := f.NewUnstructuredBuilder(true)
	if err != nil {
		return err
	}

	r := builder.
		ContinueOnError().
		NamespaceParam(cmdNamespace).DefaultNamespace().
		FilenameParam(enforceNamespace, &options.FilenameOptions).
		ResourceTypeOrNameArgs(false, args...).
		Flatten().
		Do()
	err = r.Err()
	if err != nil {
		return err
	}

	count := 0
	err = r.Visit(func(info *resource.Info, err error) error {
		if err != nil {
			return err
		}
		name, namespace := info.Name, info.Namespace
		mapping := info.ResourceMapping()
		client, err := f.UnstructuredClientForMapping(mapping)
		if err != nil {
			return err
		}

		if !options.Local {
			dataChangedMsg := "not patched"
			helper := resource.NewHelper(client, mapping)
			patchedObj, err := helper.Patch(namespace, name, patchType, patchBytes)
			if err != nil {
				return err
			}
			// Record the change as a second patch to avoid trying to merge with a user's patch data
			if cmdutil.ShouldRecord(cmd, info) {
				// Copy the resource info and update with the result of applying the user's patch
				infoCopy := *info
				infoCopy.Object = patchedObj
				infoCopy.VersionedObject = patchedObj
				if patch, patchType, err := cmdutil.ChangeResourcePatch(&infoCopy, f.Command(cmd, true)); err == nil {
					if recordedObj, err := helper.Patch(info.Namespace, info.Name, patchType, patch); err != nil {
						glog.V(4).Infof("error recording reason: %v", err)
					} else {
						patchedObj = recordedObj
					}
				}
			}
			count++

			oldData, err := json.Marshal(info.Object)
			if err != nil {
				return err
			}
			newData, err := json.Marshal(patchedObj)
			if err != nil {
				return err
			}
			if !reflect.DeepEqual(oldData, newData) {
				dataChangedMsg = "patched"
			}

			// After computing whether we changed data, refresh the resource info with the resulting object
			if err := info.Refresh(patchedObj, true); err != nil {
				return err
			}

			if len(options.OutputFormat) > 0 && options.OutputFormat != "name" {
				return cmdutil.PrintResourceInfoForCommand(cmd, info, f, out)
			}
			mapper, _, err := f.UnstructuredObject()
			if err != nil {
				return err
			}
			cmdutil.PrintSuccess(mapper, options.OutputFormat == "name", out, info.Mapping.Resource, info.Name, false, dataChangedMsg)
			return nil
		}

		count++

		originalObjJS, err := runtime.Encode(unstructured.UnstructuredJSONScheme, info.VersionedObject)
		if err != nil {
			return err
		}

		originalPatchedObjJS, err := getPatchedJSON(patchType, originalObjJS, patchBytes, mapping.GroupVersionKind, api.Scheme)
		if err != nil {
			return err
		}

		targetObj, err := runtime.Decode(unstructured.UnstructuredJSONScheme, originalPatchedObjJS)
		if err != nil {
			return err
		}

		// TODO: if we ever want to go generic, this allows a clean -o yaml without trying to print columns or anything
		// rawExtension := &runtime.Unknown{
		//	Raw: originalPatchedObjJS,
		// }
		if err := info.Refresh(targetObj, true); err != nil {
			return err
		}
		return cmdutil.PrintResourceInfoForCommand(cmd, info, f, out)
	})
	if err != nil {
		return err
	}
	if count == 0 {
		return fmt.Errorf("no objects passed to patch")
	}
	return nil
}

func getPatchedJSON(patchType types.PatchType, originalJS, patchJS []byte, gvk schema.GroupVersionKind, creater runtime.ObjectCreater) ([]byte, error) {
	switch patchType {
	case types.JSONPatchType:
		patchObj, err := jsonpatch.DecodePatch(patchJS)
		if err != nil {
			return nil, err
		}
		return patchObj.Apply(originalJS)

	case types.MergePatchType:
		return jsonpatch.MergePatch(originalJS, patchJS)

	case types.StrategicMergePatchType:
		// get a typed object for this GVK if we need to apply a strategic merge patch
		obj, err := creater.New(gvk)
		if err != nil {
			return nil, fmt.Errorf("cannot apply strategic merge patch for %s locally, try --type merge", gvk.String())
		}
		return strategicpatch.StrategicMergePatch(originalJS, patchJS, obj)

	default:
		// only here as a safety net - go-restful filters content-type
		return nil, fmt.Errorf("unknown Content-Type header for patch: %v", patchType)
	}
}